Most of those people are readers who either cannot see/refuse to see it from an author POV or are unaware of how important gems have become.
Authors simply asking readers to support them by spending 5 gems or more isn’t selfish at all considering the hours and hours of work put into stories, coding, characters, backgrounds etc, PLUS it isn’t like readers are forced to support, they can literally just choose the free choice. 
I don’t understand people who think it’s selfish—